1. Field of the Invention
The present invention relates to a method of manufacturing an endless belt member using a thermoplastic resin material, and more particularly, to a method of improving cleaning performance of a belt member by a cleaning blade.
2. Description of the Related Art
An image forming apparatus, which transfers toner images to an intermediate transfer belt and conveys the toner images, has been widely used. An image forming apparatus, which transfers toner images to a recording material by using a recording material conveying belt, has also been widely used.
These belt members are formed to have a small thickness and a large width (to have a large length in a direction along a support rotating member), are rotated at high speed while being stretched and supported by plural rotary support bodies, and need to maintain a flat conveying surface over a long time.
For this reason, the belt member in the related art has been manufactured using a thermosetting resin (for example, polyimide), which has high mechanical strength and high thermal stability, by a centrifugal molding method.
However, a method of extruding a thermoplastic resin in a cylindrical shape is preferable in terms of manufacturing cost and recyclability. Various thermoplastic resin materials having required mechanical properties and various manufacturing methods based on extruding have been proposed in recent years.
Polyetheretherketone, polyamide-imide, polycarbonate, and the like have been proposed as thermoplastic resin materials in Japanese Patent Application Laid-Open No. 2002-301764. Further, tube materials are formed by extruding a thermoplastic resin material in a cylindrical shape and cutting the extruded thermoplastic resin material to a predetermined width, and a mold surface is thermally transferred to the surface of the tube material by pressing the tube materials against the cylindrical inner circumferential surface of a heated mold one by one. Stripes, which are formed in a direction of an extruding shaft by extruding, are formed on the surface of the tube material that is extruded as it is. Since the stripes of the belt member in the width direction, which are caused by the stripes of the tube material, cause transfer unevenness of a toner image, the stripes in the axial direction are removed by thermally transferring a mirror-finished smooth mold surface.
In the case of a belt member from which a transfer residual toner or toner image for control (color patch) is removed by being rubbed with a cleaning blade, stripes in a direction of an extruding shaft are not preferable since they cause vibration of the cleaning blade. However, it has been found that the cleaning performance of the cleaning blade is stable when appropriate undulations are formed on a flat and smooth mirror surface so that stripes are formed in a rotational direction. According to experimental examples to be described below, it has been found that it is preferable that a polishing pattern in a circumferential direction be formed on the belt member so that the ten-point average roughness of the surface roughness in the width direction is in the range of about 0.3 to 1 μm.
Accordingly, there has been provided a method of forming stripes on the cylindrical inner circumferential surface of the mold disclosed in Japanese Patent Application Laid-Open No. 2002-301764 and thermally transferring the heated mold surface, on which the stripes have been formed, to the surface of a tube material made of a thermoplastic resin.
However, if the mold surface on which circumferential stripes are formed is thermally transferred, a finish has been performed so that regions to which the circumferential stripes are partially insufficiently transferred are scattered due to protrusions formed on the surface of the tube material or air parcels formed on the surface of the tube material. Further, if the regions to which the circumferential stripes are partially insufficiently transferred are scattered on the surface of the belt member, the stability of the cleaning performance to be expected is not obtained as a result.
In contrast, if a tube material manufactured by extruding is polished in a circumferential direction with a lapping tape, circumferential stripes are mechanically formed. As a result, it may be possible to reduce the unevenness of stripes on the surface (see FIG. 4). However, in this configuration, both end portions of the stripes swell or burrs are formed at the stripes due to polishing. As a result, it may not be possible to sufficiently stabilize cleaning performance.
For this reason, even though polishing for making the surface smooth is performed after a polishing process for forming stripes, it may not be possible to sufficiently remove burrs and the like.